1. Field of the Invention
The present invention relates to a high-frequency module in which a plurality of duplexers that separate transmission and reception signals in mutually-different frequency bands are provided.
2. Description of the Related Art
Nowadays, cellular phones and the like require higher capacities and higher communication speeds, leading to the exploration of carrier aggregation (CA), which simultaneously uses a plurality of communication systems of different frequency bands and, as a single communication line, transmits and receives data in a distributed manner. In a front-end module, which is provided in a location near an antenna in this type of communication device, a plurality of filter circuits, branching circuits, and the like are provided on a wiring board so that signals in a plurality of different frequency bands can be transmitted and received simultaneously.
For example, a module 100 disclosed in Japanese Unexamined Patent Application Publication No. 2006-340257 is configured to be capable of handling both W-CDMA and GSM (registered trademark) communication systems. As illustrated in FIG. 9, in the module 100, a duplexer 102 that separates W-CDMA transmission signals and reception signals, a transmission filter 103 for GSM (registered trademark) transmission signals, and two reception filters 104 and 105 for GSM (registered trademark) reception signals, are mounted on a first main surface of a wiring board 101. Meanwhile, a plurality of mounting electrodes for mounting the high-frequency module 100 onto an external motherboard or the like are provided on a second main surface of the wiring board 101, and transmission and reception terminals of the duplexer 102 and terminals of the transmission filter 103 and the reception filters 104 and 105 are connected to predetermined mounting electrodes by extended lines of the wiring board 101.
Incidentally, when transmitting and receiving using a plurality of communication systems of different frequency bands, there are cases where the frequency band of communication signals (transmission signals and reception signals) used in one communication system partially overlaps with a frequency band of a harmonic of a communication signal used in another communication system. Here, in the case where one of the communication signals is a transmission signal and the other signal that overlaps with the frequency band of the harmonic of the stated transmission signal is a reception signal, there is a risk of signal interference arising and causing a drop in reception sensitivity.
In the conventional module 100, the terminals of the duplexer 102, the transmission and reception filters 103 to 105, and so on are connected to corresponding predetermined mounting electrodes on the second main surface of the wiring board 101 by the extended lines, as described above. Accordingly, in the case where an extended line through which a transmission signal of one communication system passes is disposed near an extended line through which a reception signal overlapping with the frequency band of a harmonic of the stated transmission signal passes, there is a risk of interference arising between the signals and causing a drop in reception sensitivity. A similar drop in reception sensitivity may also occur in the case where the terminals of the duplexer 102, the filters 103 to 105, and so on through which these signals pass are disposed near one another.